From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 06AC6440647 for ; Tue, 1 Sep 2026 13:29:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788269382; cv=none; b=gqSfzD+5Stu5ZmLxCmCkHSGoVGQcYY+fT+7ujf+pXJShFXIwlB0I0ILKQvq9nIwi+IBZkklcwSv33I0D8EqzDtwE7LynO7rdmex+w3kZq8zMVGfCJX84cmBmMT8Mvx6f55D44ziyVbKc7YhBYlEST7SzmpYJXjCVfozjJ8jF34o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788269382; c=relaxed/simple; bh=9YSpV8JBddosT8Cv6FTKv08ThgtlS5ez1KfFtWuEU3k=; h=From:Subject:To:Cc:In-Reply-To:References:Content-Type:Date: Message-Id; b=APdYHsy/n8M9jzxAfFiqe/IolQ0VnYQ9ZyHkX0FMdoqUg5gwpVYtmZ6rqqTuHA+rDwNgJKSIQCYR529G6sRlUqVduRCB6+yFFHMrnFv0XtJ0ZLq3U65lbyWv0QkS/ifcUBEXh4EdwOraaBYBvXakYzuk17IyzlX52OR2pDNSQv8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Hu0Ya6SP; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Hu0Ya6SP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7D8A91F000E9; Tue, 1 Sep 2026 13:29:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788269380; bh=L7xGGpQdEiEE+TbW2bV+tBlFeNC1z2QImWIDxEHwweI=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=Hu0Ya6SPwRW0jVpwCjg9fzFdgsczcBU46sl+4itQzXhnhmCCGdSms9dQa273IYmj/ pMBpVgkI9a9NJmg2uVT1wvg+0brmSziPS0+AOpMsnwOLru/C1yH0KWcY7orkHYDGWX LvF7pu1rEVDSEltFvtdcjFzODRlKJNTRLjfJ1EzxaPVmu3gDgiA8HDNZm6RnA5pUMk 8OFA1HbS1AkZFAXm/+cDwra/5AMyGbNKNcaU9jnfBm3YA4GAFz2feybCo45GLCBwmV PTojiq3lnbAVLFX6/tXauMtgg7ujQHBq5cpxnpNDWYruDbmLGh9i828Qtm5//yYZZ2 +h/sewFmQWsFA== From: sashiko-bot@kernel.org Subject: Re: [PATCH 4/8] mm/damon/vaddr: respect folio end for DAMOS_STAT Reply-To: sashiko-reviews@lists.linux.dev To: "SJ Park" Cc: damon@lists.linux.dev In-Reply-To: <20260901131850.98037-5-sj@kernel.org> References: <20260901131850.98037-1-sj@kernel.org> <20260901131850.98037-5-sj@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Tue, 01 Sep 2026 13:29:40 +0000 Message-Id: <20260901132940.7D8A91F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: damon@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: > For applying DAMOS_STAT action to a region, DAMON virtual address space > operation set (vaddr) calls walk_page_range[_vma]() for the region. The > pmd walk entry function, namely damon_va_stat_pmd_entry(), applies DAMOS > filters to folios of addresses of the region in the pmd. It starts from > the walking address and advances the address by the size of the folio of > the address until it goes out of the pmd or the region. >=20 > Let's suppose it is for the first pmd of the region, and the region > start address is in the middle of a large folio. Also, the next folios > are small. Then, some of the next folios could be skipped. Fix the > issue by advancing the address to exactly the start address of the next > folio. >=20 > The user impact is that the DAMOS_STAT-based page level monitoring > results become inaccurate. Since the page level monitoring is supposed > to provide relatively high precision, this is definitely a problem. It > is arguably not critical since it is only monitoring quality > degradation. >=20 > The issue was discovered [1] by Sashiko. >=20 > [1] https://lore.kernel.org/20260514015053.149396-1-sj@kernel.org >=20 > Fixes: 63f39737d1e3 ("mm/damon/vaddr: support stat-purpose DAMOS filters") > Cc: # 6.18.x > Signed-off-by: SJ Park Sashiko has reviewed this patch and found no issues. It looks great! --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260901131850.9803= 7-1-sj@kernel.org?part=3D4